<template>
  <div class="spec-preview">
    <img :src="imgUrl" />
    <div class="event" @mousemove="mousemove"></div>
    <div class="big">
      <!-- 放大镜右侧图片 -->
      <img :src="imgUrl" ref="imgBig" />
    </div>
    <!-- 蒙版 -->
    <div class="mask" ref="mask"></div>
  </div>
</template>

<script>
import { mapGetters } from "vuex";
export default {
  name: "Zoom",
  data() {
    return {
      //img默认图片
      index: 0,
    };
  },
  //计算属性
  computed: {
    ...mapGetters(["skuImageList"]),
    //需要定义为计算属性,动态
    imgUrl() {
      //默认显示第一张图
      //如果直接赋值会出现假报错,第一次会获取undefined
      return (this.skuImageList[this.index] || {}).imgUrl;
    },
  },
  methods: {
    mousemove(e) {
      // console.log(e.target.offsetWidth)
      // console.log(e.target.offsetHeight)
      //大图
      let imgBig = this.$refs.imgBig;
      // mask蒙版
      let mask = this.$refs.mask;

      //纠正位置
      let x = e.offsetX - mask.offsetWidth / 2;
      let y = e.offsetY - mask.offsetHeight / 2;

      //设置两端边界
      if (x < 0) x = 0;
      if (x > e.target.offsetWidth) x = e.target.offsetWidth - mask.clientWidth;
      if (y < 0) y = 0;
      if (y > e.target.offsetHeight)
        y = e.target.offsetHeight - mask.clientHeight;

      //设置蒙版位置
      mask.style.left = x + "px";
      mask.style.top = y + "px";
    },
  },
  //挂载$bus
  mounted() {
    this.$bus.$on("addimg", (index) => {
      this.index = index;
    });
  },
  //卸载$bus
  beforeDestroy() {
    this.$bus.$on("addimg");
  },
};
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>